refactoring unit-tests - clean code days · 2016. 7. 6. · refactoring unit-tests @marcoemrich...
TRANSCRIPT
Refactoring Unit-Tests@MarcoEmrich Juni 2016 #CCD16
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TDDTDDStoneageStoneage
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Birth ofBirth ofTTest est DDriven riven DDevelopmentevelopment
??
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https://arialdomartini.wordpress.com/2012/07/20/you-wont-believe-how-old-tdd-is
John von Neuman
Anno Anno 19571957
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https://arialdomartini.wordpress.com/2012/07/20/you-wont-believe-how-old-tdd-is
Kent Beck
Anno Anno 19891989
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TDD???
Anno Anno 20052005
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6def test_validate_password @user.password = '' @user.password_confirmation = '' assert [email protected] assert_equal ["is too short (minimum is 5 characters)", "has invalid characters", "can't be blank"], @user.errors.on(:password)
@user.password = 'testest' @user.password_confirmation = 'testtest' assert [email protected] assert_equal "doesn't match confirmation" , @user.errors.on(:password)
@user.password = '' @user.password_confirmation = 'testtest' assert [email protected] assert_equal ["is too short (minimum is 5 characters)", "has invalid characters", "doesn't match confirmation", "can't be blank"], @user.errors.on(:password)
@user.password = 'testtest' @user.password_confirmation = '' assert [email protected] assert_equal "doesn't match confirmation", @user.errors.on(:password)
@user.password = 'test' @user.password_confirmation = 'test' assert [email protected] assert_equal "is too short (minimum is 5 characters)", @user.errors.on(:password)
@user.password = 'testet' @user.password_confirmation = 'testet' assert @user.saveend
webmasters.dewebmasters.de 20052005
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6def test_validate_password @user.password = '' @user.password_confirmation = '' assert [email protected] assert_equal ["is too short (minimum is 5 characters)", "has invalid characters", "can't be blank"], @user.errors.on(:password)
@user.password = 'testest' @user.password_confirmation = 'testtest' assert [email protected] assert_equal "doesn't match confirmation" , @user.errors.on(:password)
@user.password = '' @user.password_confirmation = 'testtest' assert [email protected] assert_equal ["is too short (minimum is 5 characters)", "has invalid characters", "doesn't match confirmation", "can't be blank"], @user.errors.on(:password)
@user.password = 'testtest' @user.password_confirmation = '' assert [email protected] assert_equal "doesn't match confirmation", @user.errors.on(:password)
@user.password = 'test' @user.password_confirmation = 'test' assert [email protected] assert_equal "is too short (minimum is 5 characters)", @user.errors.on(:password)
@user.password = 'testet' @user.password_confirmation = 'testet' assert @user.saveend
Embarrass
ing
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There is still hopeThere is still hope......
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Test Test RefactoringRefactoring
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ExampleExample
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(CC) https://www.flickr.com/photos/shannxn/14129007573 Shannon O'Toole
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(CC) https://www.flickr.com/photos/rockandrollfreak/16773279381
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ONLINEONLINESeminar-ShopSeminar-Shop
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ONLINEONLINESeminar-ShopSeminar-Shop
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(CC) https://www.flickr.com/photos/shannxn/14129007573 Shannon O'Toole
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SpecsSpecs
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● Seminare haben Name und Nettopreis
Ruby Java
SpecsSpecs
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● Seminare haben Name und Nettopreis
● Seminare berechnen Ihren Bruttopreis - außer, sie sind steuerbefreit
Ruby Java/JS
SpecsSpecs
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MarketingMarketingDepartmentDepartment
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3-Buchstaben Rabatt3-Buchstaben Rabatt
(CC) https://www.flickr.com/photos/hey__paul/5851687664 Hey Paul Studios
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● Seminare haben Name und Nettopreis
● Seminare berechnen Ihren Bruttopreis - außer, sie sind steuerbefreit
● 3-Buchstaben-Seminare* bekommen 5% Rabatt
Ruby Java/JS
SpecsSpecs
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6class Seminar TAX_RATE = 1.19 THREE_LETTER_DISCOUNT_RATE = 5
attr_writer :net_price, :tax_free, :name
def initialize(name, net_price, tax_free) @name, @net_price, @tax_free = name, net_price, tax_free end
def gross_price net_price * tax_rate end
def net_price @net_price - discount end
def tax_rate @tax_free ? 1 : TAX_RATE / 100 end
def discount @net_price * discount_rate / 100 end
def discount_rate discount_granted? ? THREE_LETTER_DISCOUNT_RATE : 0 end
def discount_granted? @name.size < 3 end
end
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6class Seminar TAX_RATE = 1.19 THREE_LETTER_DISCOUNT_RATE = 5
attr_writer :net_price, :tax_free, :name
def initialize(name, net_price, tax_free) @name, @net_price, @tax_free = name, net_price, tax_free end
def gross_price net_price * tax_rate end
def net_price @net_price - discount end
def tax_rate @tax_free ? 1 : TAX_RATE / 100 end
def discount @net_price * discount_rate / 100 end
def discount_rate discount_granted? ? THREE_LETTER_DISCOUNT_RATE : 0 end
def discount_granted? @name.size < 3 end
end
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Tests?Tests?
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6class SeminarTest < Test::Unit::TestCase
def test_seminar_should_calculate_correct_gross_prices seminar = Seminar.new('OOP', 500, false) assert_equal 565.25, seminar.gross_price
seminar.net_price = 300 assert_equal 339.15, seminar.gross_price
seminar.tax_free = true assert_equal 285, seminar.gross_price
seminar.name = 'Objekt-Orientierte Programmierung' assert_equal 300, seminar.gross_price end
end
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6class SeminarTest < Test::Unit::TestCase
def test_seminar_should_calculate_correct_gross_prices seminar = Seminar.new('OOP', 500, false) assert_equal 565.25, seminar.gross_price
seminar.net_price = 300 assert_equal 339.15, seminar.gross_price
seminar.tax_free = true assert_equal 285, seminar.gross_price
seminar.name = 'Objekt-Orientierte Programmierung' assert_equal 300, seminar.gross_price end
end
Failure:<565.25> expected but was<5.95>.
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3 minutes3 minutes
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Bug?Bug?
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2 Bugs?2 Bugs?
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alternativealternativetest suittest suit
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9 test cases9 test cases
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2 failing tests2 failing tests
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6def test_seminar_should_have_the_german_mwst_tax_rate_if_it_is_not_tax_free seminar = create_seminar(tax_free: false) assert_equal Seminar::TAX_RATE, seminar.tax_rateend
def test_discount_granted_should_return_true_if_name_consists_of_3_letters seminar = create_seminar(name: 'OOP') # 3 Letters assert seminar.discount_granted?end
Failure:<1.19> expected but was<0.0119>.
Failure:<false> is not true.
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3 minutes3 minutes
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Bug?Bug?
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2 Bugs?2 Bugs?
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3 Bugs?3 Bugs?
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6class Seminar TAX_RATE = 1.19 THREE_LETTER_DISCOUNT_RATE = 5
attr_writer :net_price, :tax_free, :name
def initialize(name, net_price, tax_free) @name, @net_price, @tax_free = name, net_price, tax_free end
def gross_price net_price * tax_rate end
def net_price @net_price - discount end
def tax_rate @tax_free ? 1 : TAX_RATE / 100 end
def discount @net_price * discount_rate / 100 end
def discount_rate discount_granted? ? THREE_LETTER_DISCOUNT_RATE : 0 end
def discount_granted? @name.size < 3 end
end
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6class Seminar TAX_RATE = 1.19 THREE_LETTER_DISCOUNT_RATE = 5
attr_writer :net_price, :tax_free, :name
def initialize(name, net_price, tax_free) @name, @net_price, @tax_free = name, net_price, tax_free end
def gross_price net_price * tax_rate end
def net_price @net_price - discount end
def tax_rate @tax_free ? 1 : TAX_RATE end
def discount @net_price * discount_rate / 100 end
def discount_rate discount_granted? ? THREE_LETTER_DISCOUNT_RATE : 0 end
def discount_granted? @name.size <= 3 end
end
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comparingcomparingtest suitestest suites
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Quality CriteriaQuality Criteriaforfor
test casestest cases
ReadableReadable
(CC) https://www.flickr.com/photos/camera_is_a_mirror_with_memory/6628934195
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Living Living Documentation!Documentation!
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TestingTestingthethe
Tests?Tests?
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FastFast
MaintainableMaintainable
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Defect Defect LocalizationLocalization
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IsolationIsolation(CC) https://www.flickr.com/photos/loufi/3500076/
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FocusFocus
(CC) https://www.flickr.com/photos/rogersg/3814863064
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"Jeder Test-Case prüft genau eine interessante Verhaltensweise"
J.B. Rainsberger
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Quality CriteriaQuality CriteriaReadable
Fast
Maintainable
Defect Localization
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(CC) http://www.flickr.com/photos/a_ninjamonkey/3565672226/sizes/o/in/photostream/
Conflicts?Conflicts?
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Optimaler Kompromiss?
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TDD
Kent Beck
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Meet BDD(Dan North oder King Image)
http://dannorth.net/bio/
BDD
Dan North
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TDD/BDD führen zu guten Tests!
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TDD/BDD führen zu guten Tests!
(nicht unbedingtautomatisch)
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Verbesserungen möglich!
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Legacy Test Suites
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??
Testcode muss gewartet werdenTestcode muss gewartet werden
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Test RefactoringTest RefactoringExampleExample
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6class SeminarTest < Test::Unit::TestCase
def test_seminar_should_calculate_correct_gross_prices seminar = Seminar.new('OOP', 500, false) assert_equal 565.25, seminar.gross_price
seminar.net_price = 300 assert_equal 339.15, seminar.gross_price
seminar.tax_free = true assert_equal 285, seminar.gross_price
seminar.name = 'Objekt-Orientierte Programmierung' assert_equal 300, seminar.gross_price end
end
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6class SeminarTest < Test::Unit::TestCase
def test_seminar_should_calculate_correct_gross_prices seminar = Seminar.new('OOP', 500, false) assert_equal 565.25, seminar.gross_price
seminar.net_price = 300 assert_equal 339.15, seminar.gross_price
seminar.tax_free = true assert_equal 285, seminar.gross_price
seminar.name = 'Objekt-Orientierte Programmierung' assert_equal 300, seminar.gross_price end
end
Remove Redudant Tests(gleiche Äquivalenzklasse)
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6class SeminarTest < Test::Unit::TestCase
def test_seminar_should_calculate_correct_gross_prices seminar = Seminar.new('OOP', 500, false) assert_equal 565.25, seminar.gross_price
seminar.net_price = 300 assert_equal 339.15, seminar.gross_price
seminar.tax_free = true assert_equal 475, seminar.gross_price
seminar.name = 'Objekt-Orientierte Programmierung' assert_equal 500, seminar.gross_price end
end
Remove Redudant Tests
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6class SeminarTest < Test::Unit::TestCase
def test_seminar_should_calculate_correct_gross_prices seminar = Seminar.new('OOP', 500, false) assert_equal 565.25, seminar.gross_price
seminar.tax_free = true assert_equal 475, seminar.gross_price
seminar.name = 'Objekt-Orientierte Programmierung' assert_equal 500, seminar.gross_price end
end
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6class SeminarTest < Test::Unit::TestCase
def test_seminar_should_calculate_correct_gross_prices seminar = Seminar.new('Objekt-Orientierte Programmierung', 500, true) assert_equal 500, seminar.gross_price
seminar.name = 'OOP' assert_equal 475, seminar.gross_price
seminar.tax_free = false assert_equal 565.25, seminar.gross_price end
end
Use neutral fixture(Build up!)
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6class SeminarTest < Test::Unit::TestCase
def test_a_tax_free_seminar_should_return_a_gross_price_without_tax seminar = Seminar.new('Objekt-Orientierte Programmierung', 500, true) assert_equal 500, seminar.gross_price end
def test_a_not_tax_free_seminar_should_return_gross_price_with_correct_tax seminar = Seminar.new('Objekt-Orientierte Programmierung', 500, false) assert_equal 595, seminar.gross_price end
def test_a_3letter_seminar_should_return_a_gross_price_with_discount seminar = Seminar.new('OOP', 500, true) assert_equal 475, seminar.gross_price end
end
Split test methodsFresh fixtureArrange Act Assert: AAA-Pattern
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6class SeminarTest < Test::Unit::TestCase
def test_a_tax_free_seminar_should_return_a_gross_price_without_tax seminar = Seminar.new('Objekt-Orientierte Programmierung', 500, true) assert_equal 500, seminar.gross_price end
def test_a_not_tax_free_seminar_should_return_gross_price_with_correct_tax seminar = Seminar.new('Objekt-Orientierte Programmierung', 500, false) assert_equal 595, seminar.gross_price end
def test_a_3letter_seminar_should_return_a_gross_price_with_discount seminar = Seminar.new('OOP', 500, true) assert_equal 475, seminar.gross_price end
end
Use test data factories
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Test data factories● Ruby-Frameworks
Factory-Girl Machinist
● Java-Frameworks Usurper PojoBuilder
● Patterns Object Mothers Test Data Builders/Factories Example Factories
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6class SeminarTest < Test::Unit::TestCase
def create_seminar(args = {}) new_args = { :name => 'Object Oriented Programming', :net_price => 500, :tax_free => true }.merge(args)
Seminar.new(new_args[:name], new_args[:net_price], new_args[:tax_free]) end
end
Use factories
Defaults(neutral Fixture)
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6class SeminarTest < Test::Unit::TestCase def test_a_tax_free_seminar_should_return_a_gross_price_without_tax seminar = Seminar.new('Objekt-Orientierte Programmierung', 500, true) seminar = create_seminar(tax_free: true) assert_equal 500, seminar.gross_price end
def test_a_not_tax_free_seminar_should_return_gross_price_with_correct_tax seminar = Seminar.new('Objekt-Orientierte Programmierung', 500, false) seminar = create_seminar(tax_free: false) assert_equal 595, seminar.gross_price end
def test_a_3letter_seminar_should_return_a_gross_price_with_discount seminar = Seminar.new('OOP', 500, true) seminar = create_seminar(name: 'OOP') assert_equal 475, seminar.gross_price end
end
Use factories
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6class SeminarTest < Test::Unit::TestCase def test_a_tax_free_seminar_should_return_a_gross_price_without_tax seminar = create_seminar(tax_free: true) assert_equal 500, seminar.gross_price end
def test_a_not_tax_free_seminar_should_return_gross_price_with_correct_tax seminar = create_seminar(tax_free: false) assert_equal 595, seminar.gross_price end
def test_a_3letter_seminar_should_return_a_gross_price_with_discount seminar = create_seminar(name: 'OOP') assert_equal 475, seminar.gross_price end
end
Use factories
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6class SeminarTest < Test::Unit::TestCase def test_a_tax_free_seminar_should_return_a_gross_price_without_tax seminar = create_seminar(tax_free: true) assert_equal seminar.net_price, seminar.gross_price end
def test_a_not_tax_free_seminar_should_return_gross_price_with_correct_tax seminar = create_seminar(tax_free: false) assert_equal seminar.net_price * Seminar::TAX_RATE, seminar.gross_price end
def test_a_3letter_seminar_should_return_a_gross_price_with_discount seminar = create_seminar(name: 'OOP', net_price: 500) assert_equal 500 * 0.95, seminar.gross_price end
end
Use factories
500
500
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6class SeminarTest < Test::Unit::TestCase def test_a_tax_free_seminar_should_return_a_gross_price_without_tax seminar = create_seminar(tax_free: true) assert_equal seminar.net_price, seminar.gross_price end
def test_a_not_tax_free_seminar_should_return_gross_price_with_correct_tax seminar = create_seminar(tax_free: false) assert_equal seminar.net_price * Seminar::TAX_RATE, seminar.gross_price end
def test_a_3letter_seminar_should_return_a_gross_price_with_discount seminar = create_seminar(name: 'OOP', net_price: 500) assert_equal 500 * 0.95, seminar.gross_price end
end
add missing test
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6class SeminarTest < Test::Unit::TestCase def test_a_tax_free_seminar_should_return_a_gross_price_without_tax seminar = create_seminar(tax_free: true) assert_equal seminar.net_price, seminar.gross_price end
def test_a_not_tax_free_seminar_should_return_gross_price_with_correct_tax seminar = create_seminar(tax_free: false) assert_equal seminar.net_price * Seminar::TAX_RATE, seminar.gross_price end
def test_a_3letter_seminar_should_return_a_gross_price_with_discount seminar = create_seminar(name: 'OOP', net_price: 500) assert_equal 500 * 0.95, seminar.gross_price end
def test_a_more_letters_seminar_should_return_a_net_price_without_discount seminar = create_seminar(name: 'Object O. Programming', net_price: 500) assert_equal 500, seminar.gross_price end
end
add missing test
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def test_a_3letter_seminar_should_return_a_gross_price_with_discount seminar = create_seminar(name: 'OOP') assert_equal 500 * 0.95, seminar.gross_price end
def test_a_more_letters_seminar_should_return_a_net_price_without_discount seminar = create_seminar(name: 'Object Oriented Programming') assert_equal 500, seminar.gross_price end
Isolate
class Seminar def gross_price net_price * tax_rate end
def net_price @net_price - discount end
def discount @net_price * discount_rate / 100 endend
Discount
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def test_a_3letter_seminar_should_return_a_gross_price_with_discount seminar = create_seminar(name: 'OOP') assert_equal 500 * 0.95, seminar.net_price .gross_price end
def test_a_more_letters_seminar_should_return_a_net_price_without_discount seminar = create_seminar(name: 'Object Oriented Programming') assert_equal 500, seminar.net_price .gross_price end
Isolate
class Seminar def gross_price net_price * tax_rate end
def net_price @net_price - discount end
def discount @net_price * discount_rate / 100 endend
Discount
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def test_a_tax_free_seminar_should_return_a_gross_price_without_tax seminar = create_seminar(tax_free: true) assert_equal seminar.net_price, seminar.gross_price end
def test_a_not_tax_free_seminar_should_return_gross_price_with_correct_tax seminar = create_seminar(tax_free: false) assert_equal seminar.net_price * Seminar::TAX_RATE, seminar.gross_price end
Isolate
class Seminar def gross_price net_price * tax_rate end
def tax_rate @tax_free ? 1 : TAX_RATE / 100 endend
Tax
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def test_a_tax_free_seminar_should_have_a_tax_rate_of_1 seminar = create_seminar(tax_free: true) assert_equal seminar.net_price, seminar.gross_price assert_equal 1, seminar.tax_rate end
def test_a_not_tax_free_seminar_should_have_the_correct_tax_rate seminar = create_seminar(tax_free: false) assert_equal seminar.net_price * Seminar::TAX_RATE, seminar.gross_price assert_equal Seminar::TAX_RATE, seminar.tax_rate end
Isolate
class Seminar def gross_price net_price * tax_rate end
def tax_rate @tax_free ? 1 : TAX_RATE / 100 endend
Tax
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def test_a_tax_free_seminar_should_have_a_tax_rate_of_1 seminar = create_seminar(tax_free: true) assert_equal 1, seminar.tax_rate end
def test_a_not_tax_free_seminar_should_have_the_correct_tax_rate seminar = create_seminar(tax_free: false) assert_equal Seminar::TAX_RATE, seminar.tax_rate end
Isolate
class Seminar def gross_price net_price * tax_rate end
def tax_rate @tax_free ? 1 : TAX_RATE / 100 endend
Tax
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def test_a_tax_free_seminar_should_have_a_tax_rate_of_1 seminar = create_seminar(tax_free: true) assert_equal 1, seminar.tax_rate end
def test_a_not_tax_free_seminar_should_have_the_correct_tax_rate seminar = create_seminar(tax_free: false) assert_equal Seminar::TAX_RATE, seminar.tax_rate end
Lost Coverage
class Seminar def gross_price net_price * tax_rate end
def tax_rate @tax_free ? 1 : TAX_RATE / 100 endend
Tax
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def test_a_tax_free_seminar_should_have_a_tax_rate_of_1 seminar = create_seminar(tax_free: true) assert_equal 1, seminar.tax_rate end
def test_a_not_tax_free_seminar_should_have_the_correct_tax_rate seminar = create_seminar(tax_free: false) assert_equal Seminar::TAX_RATE, seminar.tax_rate end
def test_seminar_should_use_tax_rate_to_calculate_gross_price
endclass Seminar def gross_price net_price * tax_rate end
def tax_rate @tax_free ? 1 : TAX_RATE / 100 end def net_price @net_price - discount end
Tax
Lost Coverage
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def test_a_tax_free_seminar_should_have_a_tax_rate_of_1 seminar = create_seminar(tax_free: true) assert_equal 1, seminar.tax_rate end
def test_a_not_tax_free_seminar_should_have_the_correct_tax_rate seminar = create_seminar(tax_free: false) assert_equal Seminar::TAX_RATE, seminar.tax_rate end
def test_seminar_should_use_tax_rate_to_calculate_gross_priceseminar = create_seminar(tax_free: false)
assert_equal ?, seminar.gross_price end
class Seminar def gross_price net_price * tax_rate end
def tax_rate @tax_free ? 1 : TAX_RATE / 100 end def net_price @net_price - discount end
Tax
IsolateUse Stubs
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def test_a_tax_free_seminar_should_have_a_tax_rate_of_1 seminar = create_seminar(tax_free: true) assert_equal 1, seminar.tax_rate end
def test_a_not_tax_free_seminar_should_have_the_correct_tax_rate seminar = create_seminar(tax_free: false) assert_equal Seminar::TAX_RATE, seminar.tax_rate end
def test_seminar_should_use_tax_rate_to_calculate_gross_price seminar = create_seminar(tax_free: false) seminar.stubs(net_price: 100) seminar.stubs(tax_rate: 1.5) assert_equal 150, seminar.gross_price end
IsolateUse Stubs
class Seminar def gross_price net_price * tax_rate end
def tax_rate @tax_free ? 1 : TAX_RATE / 100 end def net_price @net_price - discount end
Tax
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Mocks & Stubs● Ruby
Rspec-Mocks Mocha FlexMock
● Java Mockito EasyMock Jmockit
● JavaScript SinonJS Jasmine Spies
@m
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CC
D1
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@m
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@marcoemrich
https://github.com/marcoemrich